Field of the Invention
Embodiments of the present invention relate generally to display frame generation and more specifically to a system and method for efficiently compressing display data used in display frame generation.
Description of the Related Art
Display data that are used in display frame generation include RGB color values for each of the pixels that make up the display frame. During display frame generation, a graphics processing unit (“GPU”) reads display data from memory and generates an image that is displayed on a CRT or a similar display device from the display data. Some contemporary high performance mobile computing devices store display data locally on the GPU to reduce power consumption during display frame generation. One such system and method is described in U.S. patent application Ser. No. 11/534,128 entitled, “Screen Compression for Mobile Applications,” filed Sep. 21, 2006, the entire contents of which are incorporated by reference herein. Configuring the GPU to store display data locally reduces memory traffic to main memory, thereby reducing power consumption.
When display data are stored locally on a GPU, the display data are compressed prior to storage to reduce the amount of local memory used by the display data. Since the size of the local memory substantially affects the cost of the GPU, and the cost of the GPU is a serious consideration for purchasing consumers, minimizing the size of the local memory is an important factor in the commercial viability of the GPU. Various compression methods may be used. According to one example known as difference encoding, differences between the display data of adjacent pixels are computed, and the difference values are stored rather than storing the display data itself, based on the assumption that adjacent pixels do not show much variation in color and that storing the difference values will require less memory than storing the display data itself.